Feature Request: Ability to set default values for multiple_select preset

Currently, a good undocumented behavior of scheming when using the select preset, required is true, and having a choices list is that it will pick up the first choice list value as the default value.

This is not the case with the multiple_select preset though when required is true. It will not pick a default value and the required validator will trigger when you try to submit the form.

Would it be possible to create an explicit "default:" schema key so schema authors can add it to their scheming configuration DSL?

IMHO, it's not just good for the UI/UX, its also good for documenting the schema's behavior.

Start by tracing how the select and multiple_select presets handle required fields and choices, then inspect the schema configuration DSL and its validation path. Done means a default schema key can provide a multiple_select value and the required validator accepts the resulting form submission.

Written by the indexing model from the issue text.